Density-functional-based construction of transferable nonorthogonal tight-binding potentials for Si and SiH.

Abstract

We apply a previously reported density-functional-based scheme for the construction of common nonorthogonal tight-binding (TB) matrix elements for Si and SiH within the framework of the linear combination of atomic orbitals formalism using the local-density approximation. By only considering two-center integrals the Hamiltonian and overlap matrix elements are calculated out of suitable input densities and potentials rather than fitted to experimental data. The calculation of forces is easy and allows an application of the method to molecular-dynamics simulations. Despite its simplicity the method is proven to be sufficiently accurate and transferable to all-scale silicon and silicon-hydrogen structures including defect configurations. For an overall wide use within nonorthogonal TB schemes we derive analytical functions for the Si-Si, Si-H, and H-H Hamiltonian and overlap matrix elements.